EP0460188A1 - Compression a haute vitesse de donnees d'imagerie - Google Patents

Compression a haute vitesse de donnees d'imagerie

Info

Publication number
EP0460188A1
EP0460188A1 EP19910902065 EP91902065A EP0460188A1 EP 0460188 A1 EP0460188 A1 EP 0460188A1 EP 19910902065 EP19910902065 EP 19910902065 EP 91902065 A EP91902065 A EP 91902065A EP 0460188 A1 EP0460188 A1 EP 0460188A1
Authority
EP
European Patent Office
Prior art keywords
data
compression
signals
sub
data signals
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19910902065
Other languages
German (de)
English (en)
Inventor
David William Dellert
Frank Weiner
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Eastman Kodak Co
Original Assignee
Eastman Kodak Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Eastman Kodak Co filed Critical Eastman Kodak Co
Publication of EP0460188A1 publication Critical patent/EP0460188A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/41—Bandwidth or redundancy reduction
    • H04N1/411—Bandwidth or redundancy reduction for the transmission or storage or reproduction of two-tone pictures, e.g. black and white pictures
    • H04N1/413—Systems or arrangements allowing the picture to be reproduced without loss or modification of picture-information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/42—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals characterised by implementation details or hardware specially adapted for video compression or decompression, e.g. dedicated software implementation
    • H04N19/436—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals characterised by implementation details or hardware specially adapted for video compression or decompression, e.g. dedicated software implementation using parallelised computational arrangements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/30—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using hierarchical techniques, e.g. scalability

Definitions

  • the present invention relates in general to imagery signal processing and is particularly directed to a system for executing high speed compression of imagery data, particularly alpha-numeric text, by parallel processing of subsampled pixel data, so as to facilitate high speed data communication of the imagery data over a digital communication link, such as that employed for facsimile communication and image reconstruction.
  • Such compression units customarily use some form of one or two-dimensional Huffman encoding mechanism that has been optimized to compress the text- representative data 'across the page 1 and typically operate at a signal processing rate of up to five megabits per second, and more commonly on the order of one to two megabits per second.
  • conventional, mass market facsimile systems regardless of the input data rate, are capable of achieving a document processing rate of only about one page per minute.
  • a high data rate e.g.
  • optical scanner may be used to convert the printed text to digital data, because of the slow processing speed of the compression chip, it is necessary to buffer the input data until it can be accessed at the slower rate of the compression mechanism, thus increasing system cost without an improvement in document processing speed.
  • the signal processing system rather than directly compress successive data samples in the order they are supplied in an 'across the page', line by line format, the signal processing system according to the present invention subdivides or subsamples the data into respective sub-arrays of pixel data, the rate of occurrence of successive ones of which is lower than the original data, particularly at a rate of occurrence which is processing speed- compatible with the compression speed of readily available compression chips. These subsample arrays of data are then coupled to respective lower speed compression units to effect a parallel compression of the subsampled data.
  • the data rate of successive data values within the subsampled arrays is only a fraction of the rate at which successive data values are supplied by the optical scanning device, it is possible to make use of the above-mentioned, low cost compression units to perform the compression operation.
  • the number of compression units required will depend upon the intended data rate and the compression rate of an individual compression chip. As pointed out previously, readily available, low cost chips can typically handle data rates on the order of one to five megabits. Consequently, for a ten to twelve megabits per second communication channel the number of compression chips required will be on the order of two to ten. However, such chips are considerably less expensive than the cost of memory units that would be necessary in the course of compressing the bit map data at the high input data rates.
  • the compressed subsampled data is then combined for transmission over a high data rate communication channel to a receiver site.
  • successive portions of the compressed signals that have been transmitted over the communication channel from the transmitter site are coupled to respective ones of a plurality of parallel data decompression units, which produce decompressed output signals.
  • the decompressed output signals produced by the decompression units are coupled to a parallel-serial shift register. By serially reading out the contents of the shift register, there is obtained a reconstructed serial data stream representative of the multi-dimensional array of imagery data sample values.
  • the direction in which the data is most high correlated is generally orthogonal to the that in which the text is optically scanned (across the page) .
  • the shapes of typed or printed text tend to have a significant component in the vertical or down-the-page direction, rather than in the horizontal direction, so that successive samples of an image of a page (multiple lines) of text will usually undergo fewer transitions (e.g. dark to light) in the vertical direction than in the horizontal direction.
  • transitions e.g. dark to light
  • signals representative of a multi-dimensional array of imagery data sample values for transmission over a communication channel at a prescribed data rate are compressed by providing a plurality of data compression units, a respective one of which is capable of compressing data supplied to it at a compression rate (e.g. one to five Mb/s) that is a fraction of the transmission data rate (e.g. 10 - 12 Mb/s) .
  • a compression rate e.g. one to five Mb/s
  • a fraction of the transmission data rate e.g. 10 - 12 Mb/s
  • bit map respective pixel locations of which are associated with the signals to be transmitted, is then subsampled or subdivided by demultiplexing the successive data (pixel) values of the successive rows of the map into a plurality of sub-arrays of data successive ones of which correspond to every kth data value of the original map.
  • the data values of the sub-arrays are then coupled to respective sets of compression units, each of which is associated with a respective sub-array and is of the type which is capable of executing two- dimensional compression of its input data.
  • FIG. 1 is a block diagram of an embodiment of an imagery data communication system which employs the improved compression mechanism in accordance with the present invention;
  • Figures 2 and 3 show respective sub-arrays of bit map data demultiplexed by the system of Figure 1;
  • FIG. 4 shows an enlarged section of text.
  • FIG. 1 a block diagram of an embodiment of an imagery data communication system which employs the improved compression mechanism in accordance with the present invention is illustrated as comprising a transmitter site 10 having an imagery data source 11 (e.g. an opto-electronic document scanner which is arranged to effect raster type scan of a document, such as successively fed pages of printed text) , data source 11 producing a series of digitally encoded signals respectively representative of successively sampled grey level values of the (text) image.
  • imagery data source 11 e.g. an opto-electronic document scanner which is arranged to effect raster type scan of a document, such as successively fed pages of printed text
  • data source 11 producing a series of digitally encoded signals respectively representative of successively sampled grey level values of the (text) image.
  • each of the encoded signal values corresponds to a respective pixel location in a bit nap 13 of the scanned image, the bit map effectively comprising a two-dimensional array of pixel data, M (e.g. 1768) columns wide by N (e.g. 2200) rows deep.
  • M e.g. 1768
  • N e.g. 2200
  • this limitation in document processing speed of conventional facsimile transmission systems is dramatically increased by effectively subsampling or subdividing bit nap 13 into a plurality of sub-arrays of data, successive ones of the data contents of the sub-arrays corresponding to every kth data value of the original nap.
  • the original imagery data bit map is coupled to a demultiplexer ' 15, K respective output ports 17-1...17- ⁇ of which are coupled to a plurality of data compression units 21-1...21-K, each of which is capable of carrying out two-dimensional compression on the sub-array of data applied to it.
  • a respective one of compression units 21-1...21-K may be a readily commercially available unit, commonly employed in mass market facsimile equipment and capable of compressing data supplied to it at a compression rate (e.g. one to five Mb/s) that is a fraction of the transmission data rate (e.g. 10 - 12 Mb/s) from imagery data source 11.
  • a compression rate e.g. one to five Mb/s
  • a fraction of the transmission data rate e.g. 10 - 12 Mb/s
  • demultiplexer 15 subdivides bit map 13 into K sub-arrays of pixel data.
  • K the sub-divided bit map may be demultiplexed into a pair of respective sub-arrays 31 and 32, as diagrammatically illustrated in Figures 2 and 3," respectively.
  • the image represented by the pixel data is a typical document transmitted by facsimile, such as a page of alpha numeric characters
  • there is a substantial inherent high correlation property among successive data samples due to the 'elongated' nature of the text, in the vertical or 'down the page' direction, as exemplified by portions of alpha numeric characters lying along line L in the enlarged section of text shown in Figure 4. Consequently, even though, for respective rows of the bit map 13, the data subsamples of sub-arrays 31 and 32 are non-consecutive (e.g. pixel values PO,0, PO,2, P0,4, P0,6....
  • each compression unit 21 suffers no loss in output signal quality.
  • the compressed output signals from compression units 21 are coupled to an output multiplexer 25 to be combined for high data rate transmission (e.g.
  • a receiver modem 42 outputs the compressed data signals that have been transmitted over communication channel 40 from transmitter site 10 to a demultiplexer 44, which, under the control of a receiver site microcontroller 43, controllably separates the incoming compressed data stream into respective output segments for application, via output ports 44-1...44-K, to a plurality of data decompression units 46-1...46-K.
  • each of decompression units 46-1...46-K may be a readily commercially available unit, commonly employed in mass market facsimile equipment and capable of effecting a two-dimensional decompression of data supplied to it at a compression rate (e.g. one to five Mb/s that is a fraction of the transmission data rate (e.g. 10 - 12 Mb/s) over channel 40.
  • a compression rate e.g. one to five Mb/s that is a fraction of the transmission data rate (e.g. 10 - 12 Mb/s) over channel 40.
  • the decompressed output signals produced by the decompression units 46 are coupled to parallel input ports 52-1...52-K of a parallel-serial shift register 55. As the contents of shift register 55 are serially read out over serial output data, there is obtained a reconstructed serial data stream representative of the original bit map of imagery data sample values.
  • shift register 55 As will be appreciated from the foregoing description, by subsampling high data rate imagery data into respective sub-arrays prior to data compression, ' it is possible to employ low cost readily available compression units whose processing speed is considerably less than the transmission data rate.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Computing Systems (AREA)
  • Theoretical Computer Science (AREA)
  • Compression Of Band Width Or Redundancy In Fax (AREA)
  • Compression, Expansion, Code Conversion, And Decoders (AREA)

Abstract

Un système de traitement d'une topographie binaire de signaux de données d'éléments d'image représentatifs d'un réseau multidimensionnel de données d'imagerie (par exemple un texte alpha-numérique) pour la transmission par un canal de communication de facsimilé permet de comprimer des données d'imagerie à l'aide de plusieurs unités de compression de données, dont une unité respective est capable de comprimer des données qui sont envoyées à une vitesse de compression qui n'est qu'une fraction de la vitesse des données. La topographie binaire est sous-échantillonnée en la démultiplexant en sous-réseaux de données. Les données des sous-réseaux sont couplées sur des ensembles respectifs des unités de compression qui exécutent une compression parallèle et bi-dimensionnelle des données des sous-réseaux démultiplexées. Même si les sous-échantillons de données associés aux rangées successives de la topographie binaire ne sont pas consécutifs, et que par conséquent ils peuvent contribuer à une réduction de l'opération de compression dans le sens horizontal compte tenu du fait que les données sont du texte, des échantillons de données successifs à l'intérieur de chaque colonne d'un sous-réseau sont en corrélation inhérente à un degré plus élevé entre eux que les valeurs de données que l'on rencontre à l'intérieur des rangées respectives de l'acquisition des bits d'origine. En conséquence, l'opération de compression de données bidimensionnelles executée par chaque unité ne souffre d'aucune baisse de qualité du signal de sortie.
EP19910902065 1989-12-22 1990-12-17 Compression a haute vitesse de donnees d'imagerie Withdrawn EP0460188A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US455116 1983-01-03
US45511689A 1989-12-22 1989-12-22

Publications (1)

Publication Number Publication Date
EP0460188A1 true EP0460188A1 (fr) 1991-12-11

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP19910902065 Withdrawn EP0460188A1 (fr) 1989-12-22 1990-12-17 Compression a haute vitesse de donnees d'imagerie

Country Status (3)

Country Link
EP (1) EP0460188A1 (fr)
JP (1) JPH04504043A (fr)
WO (1) WO1991010314A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR950005621B1 (ko) * 1992-09-30 1995-05-27 주식회사금성사 영상 디코더
JPH0939307A (ja) * 1995-07-28 1997-02-10 Nec Corp プリンタ装置
GB9606465D0 (en) * 1996-03-27 1996-06-05 Memory Corp Plc Data conversion device

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3467302A (en) * 1967-05-23 1969-09-16 Merlin C Wilson Air blower
FR2036019A5 (fr) * 1969-03-03 1970-12-24 Scal Gp Condit Aluminium
GB1481226A (en) * 1973-08-31 1977-07-27 Kokusai Denshin Denwa Co Ltd System for coding two-dimensional information
JPS5295113A (en) * 1976-02-05 1977-08-10 Fujitsu Ltd Band compression transmission system
DE3684047D1 (de) * 1985-07-02 1992-04-09 Matsushita Electric Ind Co Ltd Vorrichtung zur blockkodierung.
JP2534276B2 (ja) * 1987-10-09 1996-09-11 インターナショナル・ビジネス・マシーンズ・コーポレーション オリジナル・イメ−ジのペル信号の処理方法
EP0314356B1 (fr) * 1987-10-27 1999-03-31 Canon Kabushiki Kaisha Système de codage par prédiction

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9110314A1 *

Also Published As

Publication number Publication date
JPH04504043A (ja) 1992-07-16
WO1991010314A1 (fr) 1991-07-11

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